A conventional steering system for a material handling implement, such as a tractor or the like, typically includes a pair of steerable front wheel assemblies mounted on respective opposite sides of the rigid frame of the implement. Steering is effected from the operator's control area, with this type of arrangement providing the desired steering control under many operating conditions. Experience has shown that this conventional steering assembly desirably provides stability when operating the implement at relatively high speeds, as well as when the implement is traveling over uneven terrain. However, this type of steering arrangement sometimes lacks desired control, such as during operation at relatively slow speeds on terrain with marginal traction. Additionally, steering control can be lost when the front-end loader bucket of the implement is operated such that the steerable front wheels are raised off the ground.
Because of the disadvantages associated with conventional steering under some operating conditions, many material handling implements are equipped with so-called articulated steering, wherein steering is effected by selective articulation of front and rear portions of the frame of the implement. This type of steering can be very effective on terrain which offers minimal traction, and permits the implement to be "rocked" (i.e., articulated back-and-forth) should the implement become stuck in mud or the like. Additionally, articulated steering can still be effected should the front wheels of the implement be raised off the ground such as during operation of its front-end loader.
As will be recognized, greatly enhanced versatility can be obtained by providing an implement with both articulated and conventional steering systems. Additionally, further versatility is achieved if both conventional and articulated steering can be selectively coordinated. To this end, the present steering system is configured to provide multiple modes of steering action, including conventional, articulated, and selective coordination of both.